1. Field of the Invention
The present invention relates generally to optical devices and, more specifically, the present invention relates to an optical device that can adjust a phase of an optical beam.
2. Background Information
The need for fast and efficient optical switches is increasing as Internet data traffic growth rate is overtaking voice traffic pushing the need for optical communications. Two commonly found types of optical devices are mechanical devices and electro-optic devices.
Mechanical devices such as switching devices generally involve physical components that are placed in the optical paths between optical fibers. These components are moved to cause switching action. Micro-electronic mechanical systems (MEMS) have recently been used for miniature mechanical switches. MEMS are popular because they are silicon based and are processed using somewhat conventional silicon processing technologies. However, since MEMS technology generally rely upon the actual mechanical movement of physical parts or components, MEMS are generally limited to slower speed optical applications, such as for example applications having response times on the order of milliseconds.
In known electro-optic devices such as switching devices, interferometers, phase-shifters, etc., voltages are continuously applied to selected parts of a device to create electric fields within the device. The electric fields change the optical properties of selected materials within the device and electro-optic effect the optical beams. Electro-optic devices typically utilize electro-optical materials that combine optical transparency with voltage-variable optical behavior.
Optical phase shifters made from various materials such as Lithium Niobate (LiNbO3), liquid crystals and Indium Phosphide (InP) may be driven with an analog control voltage where the phase shift is determined by the voltage level. The use of a single analog voltage is a comparatively simple and flexible control method. In most applications, a power supply, waveform generator, or servo loop can supply the voltage. When using the phase shifter in a complex system, however, digital signal processing techniques are often desired and a digital-to-analog converter (DAC) is used to generate the analog control signal.